When a car careens out of control over an embankment, killing a middle-aged man in the driver's seat, Megan learns that all is not well on a pretty suburban cul-de-sac. Looking past the perfect picket fences, she and her team are startled by the lives spinning out of control and the ever-changing suspect roster.
一名叫尼基的女大學生被人割喉嚨掏大腦，梅根想起珍妮弗的案子手法也是如此，令人震驚的是尼基竟然是珍妮弗的女兒。梅根去找殺害珍尼弗的威爾森尋找線索，對方說自己是清白的，他要求梅根向他道歉。尼基的同學杰克、…
費城死亡的人數仍在上升，凱特病發暈倒，就連梅根也束手無措。聯邦特工提出一個構想，也許恐怖份子就在這些感染者中。莫里斯在抓捕恐怖份子時發現了病毒血樣，疾控中心主管斯塔福德認出這種病毒叫做馬爾堡，目前沒有…
